weka
- Also called:
- woodhen, Māori hen, or bush hen
- Related Topics:
- flightless bird
- rail
weka, (Gallirallus australis), species of nonmigratory flightless bird of the rail family (Rallidae) that is endemic to New Zealand. The weka is roughly the size of a chicken (Gallus gallus), and its appearance is characterized by its variable, but mainly brown, plumage with black streaks. The species is known for its feisty and curious nature and its penchant for stealing crops, food, and other small objects that appeal to it. Weka inhabit a variety of typically wet and moist habitats, such as forests, wetlands, and marine intertidal areas, but they can be found also in some shrublands, grasslands, farmlands, and suburban environments on more than 70 islands in New Zealand.
Weka are divided into four subspecies: the North Island weka (Gallirallus australis greyi), which inhabits the eastern side of North Island; the western weka (G. australis australis), a common bird with nearly black plumage that inhabits the northern and western parts of South Island; the buff weka (G. australis hectori) of Chatham and Pitt islands; and the Stewart Island weka (G. australis scotti), which inhabits Stewart Island and smaller islands nearby.
Natural history
Adult weka measure between 46 and 60 cm (18.1 and 23.6 inches) in length and weigh between 0.43 and 1.4 kg (0.95 and 3.1 pounds). Their average weight varies by subspecies but is generally about 1 kg (2.2 pounds) for males and 0.7 kg (1.5 pounds) for females. Although plumage coloration also varies between subspecies, all adult weka have red eyes, reduced wings, and a broad pointed bill. Weka have well-known calls that are loud and repetitive and sound like “coo-et.” These vocalizations, made at dawn and dusk, are call-and-response duets between males and females, with the lower-pitched part belonging to the males.
Although they cannot fly, weka can quickly walk long distances, and they are strong swimmers. Omnivorous, their diet is largely made up of plants, including grasses, leaves, berries, and seeds; they also eat a variety of invertebrates (such as earthworms, beetles, and snails), vertebrates (such as small lizards, rodents, and even smaller birds and the eggs of ground-nesting birds), and carrion. On some islands where weka have been introduced, they have become pests to other wildlife. In some cases they have had such a negative effect on native animals that the weka were eradicated. Weka are seed dispersers, and they can spread seeds too large to be dispersed by smaller birds(see also seed dispersal).
The animals that prey weka include a variety of introduced species, such as dogs, cats, ferrets, and stoats. Weka also served as an important food source for some Māori—who used the bird for its meat, skin, feathers, and oil—and as a food source for European settlers, who referred to the bird as the woodhen or bush hen. The harvest of the bird is still allowed on some offshore islands.
Weka are monogamous, with most pairs staying together for life. Both males and females can breed before they reach one year of age; however, the timing of breeding period varies across the species. Some populations with adequate numbers of adults in habitats characterized by reasonable climates and ample food resources breed year-round, with some females producing as many as four clutches of eggs per year. Among populations with less access to resources, the breeding period takes place between November and February each year or may occur once every few years. After fertilization, a female weka often lays one to three pinkish eggs in a ground nest that her mate constructs with grasses and leaves; however, some females can lay as many as six eggs. Daytime egg incubation is carried out by the female, and the male incubates the eggs at night. The chicks hatch one month later, and they are cared for by both parents until the chicks reach maturity and go off on their own, when they are between 6 and 10 weeks old. Most weka can live for about 14 years; however, there are reports of at least one living to age 19.
Conservation status
The International Union for Conservation of Nature and Natural Resources (IUCN) has listed the weka as a vulnerable species since 2000. This assessment largely stemmed from population crashes occurring among the North Island weka and western weka subspecies at the end of the 20th century, which were caused by a combination of several factors, including habitat loss, hunting and trapping, poisoning, vehicle strikes, and invasive species (both predators and competitors). Although the species’ total population remains fairly large, estimated at between 107,000 and 177,000 (with roughly two-thirds being mature individuals), the IUCN notes that weka populations living on New Zealand’s North and South islands are severely fragmented and are decreasing (albeit at a slower rate). Weka numbers are expected to decline further because of ongoing habitat loss and hunting, inbreeding, and the effects of climate change. Of the four subspecies, the Stewart Island weka is the most at risk, numbering fewer than 8,000 birds.
New Zealand wildlife authorities began a captive breeding program for the North Island weka and the buff weka during the 1990s, and a recovery plan created by the New Zealand Department of Conservation was approved in 1999. The goal of the plan is to restore healthy populations of each subspecies in their natural ranges. In an effort to reduce population fluctuations, weka that are part of the program are being introduced to mainland and island sites with stable, wet climates and rich soils to reinforce existing populations or to attempt to establish new ones.